Simultaneous introduction of nitrogen and chlorine into cotton to produce dry wrinkle recovery by treatment with urea,a urea precursor or a urea derivative and epichlorohydrin



United States Patent Otfice US. Cl. 8116.2 Claims ABSTRACT OF THE DISCLOSURE Improving the dry and wet creasing recovery of cellulosic fabrics by impregnating said fabrics with an aqueous solution of ammonium cyanate, urea or a urea derivative and thereafter causing epichlorohydrin to react therewith.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

An object of this invention is to prepare at will cellulosic fabrics with improved dry and wet crease recovery. A further object of this invention is to prepare at will cellulosic fabrics with improved dry and wet crease recovcry and which retain both nitrogen and chlorine.

By use of aqueous solutions of NH CNO, urea or substituted ureas, it is possible to cause epichlorohydrin to react with cellulose. The reaction takes place at 95 C. and at various periods of time to produce fabrics with improved dry and wet crease recovery and which retain both nitrogen and chlorine. These fabrics could be useful as pretreatments for permanent press operations, ion exchange fabrics, and rot or mildew resistant fabrics. Various ureas have been used with success and include urea, ethylene urea, propylene urea, and tetra-methyl urea. Aqueous urea alone under these conditions is unreactive towards cotton cellulose.

The object of this invention may be accomplished by padding a cotton fabric to a 100% pickup with aqueous solution of NH CNO or urea and then immersing the padded fabric in a cylinder containing epichlorohydrin which had been heated to 95 C. The fabric is allowed to react for 24 hours while maintaining the temperature at 95 C. The fabric is removed from the container and washed with water, acetic acid, methanol, and finally with water. Half of the nitrogen content of the fabric was exchangeable while the other half is in the amide form. The fabric showed weak ion exchange properties.

Urea and epichlorohydrin themselves are not reported to interact below M.P. 132 C., in fact urea dissolves only slightly in hot epichlorohydrin (100 C.) and precipitates unchanged on cooling, but we have found in this laboratory that aqueous urea solutions at 100 C. rapidly solubilize epichlorohydrin into the aqueous layer. The main reaction products are 1,3-dichloropropanol, l-chloro glycerol, glycerol, and urea. The urea appears to catalyze the addition of water to epichlorohydrin. Similar products are also obtained when aqueous tetramethyl urea 3,545,912 Patented Dec. 8, 1970 solubilizes epichlorohydrin. The solution becomes somewhat alkaline (pH 8.0-8.5) although the original urea solution is pH 7.1.

It is believed that in a warm aqueous urea, the following equilibria exist:

and in which only 5% of the whole is in the isocyanate form, i.e., the equilibrium lies mostly to the left above.

If these ideas are true, it is difficult to understand why in such a system containing cellulose, nitrogen is added to the cellulose unless there is a still further reaction between the isocyanate and some of the epichlorohydrin. One known reaction for aqueous KCNO or HCNO and epichlorohydrin results in a small yield of 4-chloro methyl-2-oxazolidone. In the process of ring closure to form the oxazolidone, it is possible that a charged species exists which reacts with cellulose instead of cyclizing to the known compound. Evidence that this is correct comes from the slowness of addition of the N and Cl containing moiety. The sequence-is dependent on several equilibria and succeeds in a round-about fashion although the addition to cotton cellulose is real enough over a period of time (10-12% in 24 hrs.).

From a comparison of the results obtained with ammonium cyanate and the various ureas used to catalyze the cellulose-epichlorohydrin reaction, it is evident that the ammonium cyanate is the active ingredient or intermediate in the formation of the oxazolidone which eventually causes nitrogen and chlorine to react with the cotton.

The following examples serve to illustrate but not limit the scope of this invention.

EXAMPLE 1 An x 80 cotton printcloth sample was twice padded to a 100% wet pickup with 14.5% (by volume) aqueous ammonium cyanate and then immersed in a graduated cylinder containing ml. of epichlorohydrin which had been preheated to C. The cotton is allowed to react for 24 hours and is then removed from the cylinder and washed with water, acetic acid, methanol, and again with Water. The fabric after drying and equilibrating' had a weight add-on of 41%, a nitrogen content of 1.5%, and a chlorine content of 0.5%. The dry crease recovery was 271 degrees (warp+fill) and the wet crease recovery was 281 degrees (warp-i-fill).

Table I shows results of fabrics treated as in Example I with varying reaction times and/ or concentration of ammonium cyanate:

TABLE I Reac- Ammonium tion Weight cyanate time, add on Dry Wet Percent Percent percent hrs. percent angle 1 angle 1 N 01 Warp plus fill, degrees.

EXAMPLE 2 An 80 x 80 fabric was twice padded to a wet pickup with 20% by volume aqueous urea solution and then immersed in a graduated cylinder containing 90 ml.

of epichlorohydrin which had been heated to 95 C. The cotton is allowed to react for 24 hours at 95 C. and is then removed from the cylinder and washed with water, acetic acid, methanol, and again with water. The fabric after drying and equilibrating had a weight add-on of 12.9%, a nitrogen content of 0.72%, and a chlorine content of 0.32%. Half of the nitrogen content was exchangeable while the other half is in the amide form. The fabric showed weak ion exchange properties.

Table II shows results of fabrics treated as in Example 1 except that other ureas were substituted for the parent compound.

1. A process for preparing a chemically treated cellulosic textile fabric that exhibits improved dry and wet crease recovery and retains nitrogen and chlorine comprismg:

(a) padding the fabric with urea, ammonium cyanate,

tetramethylurea or a lower alkylene cyclic urea,

(b) immersing the fabric in epichlorohydrin preheated to and maintained at a temperature of about 95 C., (c) washing the padded fabric with water, acetic acid,

methanol, and finally with water, (d) drying and cquilibrating the fabric. 2. The process of claim 1 wherein the fabric is padded with ammonium cyanate.

3. The process of claim 1 wherein the fabric is padded with the lower alkylene cyclic urea, ethyleneurea.

4. The process of claim 1 wherein the fabric is padded with the lower alkylene cyclic urea, propyleneurea.

S. The process of claim 1 wherein the fabric is padded with tetramethylurea.

References Cited UNITED STATES PATENTS 12/1966 Goodman et a1. 812O OTHER REFERENCES GEORGE F. LESMES, Primary Examiner JAMES CANNON, Assistant Examiner US. Cl. X.R. 8l20 

